Tuesday, 19 August 2014

A 'Nano Vaccine' That Combats Dust Mite Allergies

Scientists
at the University of Iowa have developed a vaccine that combats dust
mite allergies by naturally switching off the body's immune response.
It's welcome news for the millions of people who suffer from
mite-induced breathing difficulties.

Nearly
84% of households in the United States contain dust mites — microscopic
organisms that feed on organic leftovers like flakes of human skin.

They're a
common cause of asthma and allergic symptoms; their guts contain potent
digestive enzymes that hang-out in their feces — a major contributor to
allergic reactions such as wheezing.

But
in animal tests, researchers demonstrated that a nano-sized vaccine
package can lower lung inflammation by 83% despite repeated exposure to
the allergens. The response happens because the vaccine package contains
a booster that alters the body's inflammatory response to dust-mite
allergens.

"Our
research explores a novel approach to treating mite allergy in which
specially-encapsulated miniscule particles are administered with
sequences of bacterial DNA that direct the immune system to suppress
allergic immune responses," noted co-author Peter Thorne in a statement. "This work suggests a way forward to alleviate mite-induced asthma in allergy sufferers."

The
UI-developed vaccine takes advantage of the body's natural inclination
to defend itself against foreign bodies. A key to the formula lies in
the use of an adjuvant—which boosts the potency of the vaccine—called
CpG. The booster has been used successfully in cancer vaccines but never
had been tested as a vaccine for dust-mite allergies. Put broadly, CpG
sets off a fire alarm within the body, springing immune cells into
action. Those immune cells absorb the CpG and dispose of it.

This
is important, because as the immune cells absorb CpG, they're also
taking in the vaccine, which has been added to the package, much like
your mother may have wrapped a bitter pill around something tasty to get
you to swallow it. In another twist, combining the antigen (the
vaccine) and CpG causes the body to change its immune response,
producing antibodies that dampen the damaging health effects dust-mite
allergens generally cause.

In
lab tests, the CpG-antigen package, at 300 nanometers in size, was
absorbed 90 percent of the time by immune cells, the UI-led team
reports. The researchers followed up those experiments by giving the
package to mice and exposing the animals to dust-mite allergens every
other day for nine days total. In analyses conducted at the UI College
of Public Health, packages with CpG yielded greater production of the
desirable antibodies, while lung inflammation was lower than particles
that did not contain CpG, the researchers report.